Photodynamic therapy inhibits cancer progression and induces ferroptosis and apoptosis by targeting P53/GPX4/SLC7A11 signaling pathways in cholangiocarcinoma.

ABSTRACT

BACKGROUND: Cholangiocarcinoma (CCA) is a malignant tumor with a poor prognosis. The specific mechanism of photodynamic therapy (PDT) in treating CCA remains unclear. This study aims to investigate the mechanisms of PDT in the treatment of CCA and try to improve the therapeutic effect of PDT by intervening associated signaling pathways. METHODS: The Cell Counting Kit-8 (CCK-8) was used to examine the cytotoxicity of CCA cell lines following PDT. Apoptosis and reactive oxygen species (ROS) levels were measured by flow cytometry. A transmission electron microscope was used to study the changes in cell mitochondria after PDT. The levels of glutathione (GSH), malondialdehyde (MDA), ferrous iron (Fe2+), lactate dehydrogenase (LDH), and lipid peroxide (LPO) were determined. Changes in the expression of apoptosis and ferroptosis-related proteins were determined using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Xenograft tumor models were developed to investigate the effects of PDT on tumor proliferation, apoptosis, and ferroptosis in vivo. RESULTS: PDT inhibited tumor proliferation and induced apoptosis both in vivo and in vitro. This treatment led to swelling and damage of the mitochondria in affected cells. Furthermore, ROS levels rose, accompanied by an increase in the proportion of apoptotic-positive cells. The expressions of Bax and Caspase-3 were upregulated, while the Bcl-2 was downregulated. Meanwhile, PDT triggered ferroptosis, marked by decreased expressions of GPX4 and SLC7A11, and reduced GSH levels. This was accompanied by upregulation of P53 expression and heightened levels of Fe2+, LPO, MDA, and LDH. After inducing the ferroptosis pathway, the therapeutic effect of PDT was enhanced, the tumor tissue was further reduced, and the degree of malignancy was reduced. CONCLUSION: PDT promotes apoptosis and ferroptosis of cholangiocarcinoma cells by activating the P53/SLC7A11/GPX4 signaling pathway and inhibits the growth of cholangiocarcinoma. Inducing ferroptosis can enhance the effectiveness of photodynamic therapy.